The use of ion exchange beads to clean up aqueous solutions is a well known art. The ion exchange beads are usually employed in the form of uniformly sized particles or beads. In these techniques, anionic, cationic or mixtures of ionic species are removed from aqueous solutions by contacting the solution with the ion exchange beads usually in the form of a bed of the beads which exchanges desirable or non-harmful ionic species for the non-desirable ion species in the solution. Such clean-up techniques are used in the metal finishing industry, municiple water clarification plants, nuclear power industry and the like. One of the most frequent means of providing contact between the ion exchange beads and the solution is to flow the solution through a column which is packed with the ion exchange beads to form an ion exchange bed. When the ion exchange bed becomes spent (i.e., no longer has capacity for removing ionic species from the solution) it may be regenerated or discarded. In some areas such as when the ionic species are toxic, e.g., lead, chromium, uranium, radioactive or the like, it is desirable to discard the ion exchange bed at a suitable disposal site. U.S. Pat. No. 3,664,870 teaches the use of solvents and ion exchange beds for removing radioactive deposits from cooling systems of nuclear reactors.
Present techniques for disposal generally comprise dewatering the ion exchange bed as best as possible and placing the spent ion exchange beads in suitable containers for disposal. The ion exchange beads are usually associated with a substantial amount of free water which is difficult to remove from the beads. In some instances, the container along with the ion exchange bed is disposed of in its entirety. However, with increasing interest in environmental quality, an emphasis has been placed on disposing of such spent ion exchange beads in a form to prevent leaching of toxic ions from the container and into the environment. One means for reducing the rate at which leaching occurs is to encapsulate the ion exchange beads in a suitable binder material such as cement, various resins such as vinyl ester resins, unsaturated polyester resins, and the like.
One of the more successful methods and solidification resins for encapsulating ion exchange beads is taught in U.S. Pat. No. 4,077,901. This patent describes a method whereby the beads are encapsulated in a vinyl ester resin, or in an unsaturated polyester resin, or in a mixture of the two types of resins. Useful solidification resins are taught in U.S. Pat. Nos. 3,792,006 and 3,442,842. In this process the ion exchange beads are removed from the original container (e.g., column, etc.) and then mixed with the solidification resin in a suitable container by using a means for agitating the beads and resin to provide sufficient shear to emulsify free water remaining with the beads and form a uniform suspension of the solidification resin and beads. This process necessitates further handling of the toxic materials, the use of impellers and complicated mixing equipment, and the emulsification of substantial amounts of water along with the beads. Much of the solidification resin is used to solidify the free water. This increases the volume of solidification resin needed and therefore the overall cost of solidifying and disposing of these wastes. It would be desirable to be able to dewater, where necessary, and encapsulate spent ion exchange beads in a container without the necessity for agitating the mixture such as with an impeller and without the need for elevated temperatures such as employed in the process taught in U.S. Pat. No. 4,119,560. The present invention provides a method of doing this.